# Docker

Version

docker version
docker info

Network

• Docker uses docker0 virtual bridge interface. Each new container gets one interface automatically attached to the docker0 virtual bridge.
• Create network that other container will attach to and will be visible via name: docker network create -d bridge my-net (-d Network Driver: bridge)
• Attach container to custom network: docker run --network my-net ...

Socket Docker socket from within a container: -v /run/docker.sock:/run/docker.sock

Manage Docker as a non-root user The docker daemon binds to a Unix socket instead of a TCP port. By default that Unix socket is owned by the user root and other users can only access it using sudo. The docker daemon always runs as the root user.

If you don’t want to use sudo when you use the docker command, create a Unix group called docker and add users to it. When the docker daemon starts, it makes the ownership of the Unix socket read/writable by the docker group.

• Add the docker group if it doesn't already exist:

sudo groupadd docker

• Add the connected user "$USER" to the docker group. Change the user name to match your preferred user if you do not want to use your current user:

sudo gpasswd -a $USER docker

• Log out/in to activate the changes to groups.

• You can use docker run hello-world to check if you can run docker without sudo.

# Dockerfile

Better way of installing things when building docker images:

RUN set -ex; \ # Fail when exit status not 0, print each command (debug)
	apt-get update; \
	apt-get install -y --no-install-recommends \

# Tag, Build & Push

Run docker build inside a directory containing single file called Dockerfile

# Run

Examples:

# RUN
docker run -d --name my_container -v $PWD:/directory image:tag # Detached (in background)
docker run -it image:tag bash # Run bash shell inside of a container
docker run -d alpine:latest sh -c 'while true; do date; sleep 1; done'
docker run -p 8080:80 --name -e VAR=Value my_container image:tag  # docker run -p 8080:80
docker run --restart=always redis

# COPY
docker cp foo.txt mycontainer:/foo.txt                        # Copy from host to container
docker cp mycontainer:/foo.txt foo.txt                        # Copy form container to host

# Manage

# System

# Docker-Compose

User version 2 over version 3. The version 3 is used when using docker swarm and removes syntax used in version 2.

# Logs

Show last 100 logs from docker-compose deployment

docker-compose logs
-f            # Follow log output
-t            # Show timestamps
--tail="100"  # Number of lines to show from the end of the logs
              # for each container

# Tips & Tricks

# ALIASES in .bashrc or .zshrc
alias dps='docker ps --format "table {{.Names}}\t{{.Image}}\t{{.Ports}}"'